This invention relates to a vehicle mirror such as a fender mirror and a door mirror and, more particularly, to a vehicle mirror with an improved waterdrop prevention property.
When a waterdrop is formed on an outer mirror, e.g., a fender mirror or a door mirror, while a vehicle is running in the rain, visibility of a rear view thereby is reduced with the result that safety of driving is impaired. Therefore, for removing a waterdrop formed on the vehicle mirror, the following methods have been proposed in the past:
(a) A cleaning agent (surfectant or a washer liquid) is sprayed or otherwise applied on the surface of an outer mirror to remove a waterdrop and dust deposited on the surface of the outer mirror (e.g., Japanese Utility Model Publication No. 47-34209). PA0 (b) An anti-fog film (water absorption film) made of an organic material is attached to the surface of an outer mirror. PA0 (c) A heat generating means is provided on the back of an outer mirror to evaporate a waterdrop formed on the surface of the outer mirror (Japanese Utility Model Publication No. 51-45803). PA0 (d) An ultrasonic vibrator and a heat generating member are provided on the back of an outer mirror to scatter and evaporate a waterdrop deposited on the outer mirror.
The proposed method (a) using a cleaning agent is inconvenient because a period of time during which a waterdrop is eliminated is relatively short and, therefore, the cleaning agent must be applied frequently. The proposed method (b) using an anti-fog film has the disadvantage that the anti-fog film is susceptible to scratches and has a poor heat-resisting property because it is made of an organic film. Moreover, adhesive used for attaching the film causes diffusion of light with the result that glaring of an image occurs at night and contrast of an image is adversely affected in the daytime. Furthermore, if wetting property of the film decreases even slightly, it becomes difficult to recover sufficient visibility.
The proposed method (c) using a heat generating means for evaporation of a waterdrop usually takes seven to ten minutes for evaporating a waterdrop deposited on the outer mirror and hence is not practical. The proposed method (d) using an ultrasonic vibrator and a heat generating member requires a complex device and a large number of component parts which inevitably results in a high manufacturing cost.
It is, therefore, an object of the invention to provide a vehicle mirror capable of obtaining a sufficient and durable waterdrop removal effect with a simple structure.